Dendrochronology jaspreet

Dendrochronology

1. Dendrochronology It’s a Greek word: study of age of tree.. Dendeon means tree + chronos means time +logy means study

2. Dendrochronology: 🌳 It is the branch of science that’s deals with the study of annual rings of trees for finding out the age of tree. 🌳 Dendrochronology is an invaluable tool for the scientists to find out the age of trees. 🌳Crossdating is the most basic principle of Dendrochronology. Crossdating is a technique that ensure each individual tree ring assigned it’s exact year of formation. This is accomplished by matching the pattern of wide and narrow rings between cores from the same tree.

3. 🌳 Somehow not only the age Dendrochronology also tells about the climate where the tree is growing. A plant grows well and annual rings are formed properly where the climate is warm and wet,but are poorly developed if the climate is cold and dry. The plants growing in tropic region don’t have annual rings, because there is continuous growth season and thus no such pattern of more or less growth is formed, similarly the plants growing in very cold regions also don’t have annual rings as there is no growth season at all. Only plants growing in temperate zone have annual rings due to climate change..

4. Types of woods in trees: Sapwood : when a tree is young certain cells within the wood are alive and capable of conducting sap and storing nutrients and that wood is referred to as sapwood. Sap wood is also termed as Alebernum. Heartwood: Heartwood is also called as duramen. Dead central wood of trees. As new sapwood is formed under the bark,the inner sap wood changes to heartwood. In the wood undergoing this change the living cells die.

5. Structure and development of sapwood : Sapwood is a new wood and is like a pipeline which moves the water through tree up to the leaves. Sapwood is lighted coloured and formed of living cells associated with vessels and fibres. Sapwood commonly ranges from 4-6cm in radial thickness. Many secondary growth trees of merchantable size are mostly composed of sapwood.

6. Sapwood is formed due to cambial activity of secondary xylem.

7. Functions: * Sapwood performs the physiological activities,such as conduction of water and nutrients,storage of food etc. The sapwood in the centre of trees dies forming heartwood and as the cells die release chemicals Taht change the colour of wood as week as making the wood more stronger and more resistant to attack of insects. Th proportion of heartwood to sapwood in main stem does vary with species. For example- Black locust usually have a very narrow band often less than an inch,while that in maple stem have many inches of sapwood and relatively narrow cores of heartwood.

8. Structure and development of heartwood: Heartwood is formed due to accumulation of various compounds,such as oils,gums and resins etc. The oils,resins and colouring substances infiltrate the walls and gums and resins may fill the lumina of cells in heartwood.

9. Due to transformation a number of changes occur- all living cells lose protoplasts,water content of cell walls are reduced,food materials are withdrawn from the living cells,tyloses are frequently ford which block the vessels the parenchyma,walls become lignified,oils,gums,tannins,resins and other substances develop in cells.

10. Functions: The function of heartwood is no longer of conduction it gives only mechanical support to stem.. Heartwood consists of inactive cells Taht donor function in either water conduction or food storage. The compounds including resins,phenols and terpenes not only make heartwood more resistant to attack by insects and decay organisms but also tend to give this inner portion of stem a distinctive darker colour.

11. Due to hard nature of heartwood,it is oftenly used as timber. Because it is hard and does not consist of any moisture . While that of sapwood is made of living cells and contains moisture,if the furniture is formed it may shrink and pest can easily attack and it can also be decayed........

12. Diffuse wood: The vessels are uniformly distributed throughout the wood. Vessels are formed through growth ring. Ring wood: This wood is defined as wood in which the vessels are larger in early wood than that of late wood. This ring wood is mainly present in regions with contrasted seasons.

13. In ring porous wood trees the vessels laid down at the beginning of growing season are much larger than subsequent vessels laid down at the end of season. Most of ring porous trees are found in North temperate areas of the world. In a number of species the vessels become occluded by cellular ingrowths from surrounding living cells.

14. Diffuse porous forms the vessels of roughly the same radial diameter throughout growing season. Larger vessel size permits more rapid water conduction, because the rate of conduction varies with radius of vessel.

15. Difference between ring and porous wood Ring porous wood: In it vessels are of differen diameters. 2.The vessels are not uniformly distributed. 3.The vessels are wide and smaller of late and early wood. 4.Development of vessels is sudden and rapid. 5.Vessels are longer in length. Diffuse porous wood: Vessels are more or less equal in diameter. The vessels are uniformly distributed. Vessels of late and early wood are indistinguishable. Development is very slow. Vessels are of shorter length.

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